S1M8837 Samsung Semiconductor, Inc., S1M8837 Datasheet - Page 11

• Manufacturer Part Number: S1M8837
• Description: Fractional-n Rf/integer-n If Dual Pll
• Manufacturer: Samsung Semiconductor, Inc.

FRACTIONAL-N RF/INTEGER-N IF DUAL PLL
FUNCTIONAL DESCRIPTION
The Samsung S1M8836/37 is RF/IF dual frequency synthesizer IC which supports Fractional-N mode for RF PLL
and Integer-N mode for IF PLL depending on a program control. S1M8836/37 combined with an external LPF and
an external VCO forms PLL frequency synthesizer. The frequency synthesizer consists of prescalers, pulse-
swallowed programmable N counters, programmable reference R counters, phase detectors, programmable
charge pumps, analog LD(lock detector), serial data control, etc.
An input buffer in the prescaler amplifies the RF input power of -10dBm from the external RF/IF VCO to the
sufficient ECL switching level to drive the following ECL divider so that it can be normally operated even in a
smaller input power less than -10dBm. The amplified VCO output signal is divided by the prescaler with a pre-
determined divide ratio (div. 8/9/12/13 for S1M8836, div. 16/17/20/21 for S1M8837, div. 8/9 for IF), the N counter
and the Fractional-N circuitry(
comparison frequency of the PFD. The divide ratios of the programmable counters can be programmed via the
serial bus interface. These two signals drive the both inputs of the phase detector. The phase detector drives the
charge pump by comparing frequencies and phases of the above two signals. The charge pump and the external
LPF make the control voltage for the external VCO and finally the VCO generates the appropriate frequency
signal.
CLOCK
OSC
DATA
f
f
in
in
RF
RF
in
LE
f
f
in
in
IF
IF
+
-
+
-
Prescaler
Prescaler
RF
-
Serial Data Control
IF
modulator). External reference signal is divided by the R counter to set the
R Counter
R Counter
RF
IF
N Counter
Modulator
N Counter
RF
-
IF
Detector
Phase
IF
Detector
Phase
RF
Multiplexer
Data Out
f
o
LD
LD
IF
RF
LD
Charge
Charge
CMOS
Output
CMOS
Output
Pump
Pump
MUX
MUX
RF
IF
S1M8836/37
OUT0
OUT1
CP
CP
f
o
LD
o
o
RF
IF
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